The present invention relates to prosthetic devices, and in particular, to a combination prosthesis and osseointegrated internal fixation means.
Prostheses, such as artificial eyes, ears, and the like, require some means of attachment to the patient. Such attachments should be both functional and aesthetic. Aesthetic considerations require that the prosthesis look as nearly as possible identical to the patients natural anatomy. Functional considerations include a comfortable and secure fit and restoration of normal uses associated with the lost or damaged anatomy. Desirably, the fit of the prosthesis is secure but the prosthesis is removable as required by the patient.
One technique for attaching prostheses involves osseointegrated implants. Osseointegrated implants are surgically implanted into the patient's bony structure. These osseointegrated implants provide the anchoring point for the prosthesis.
Osseointegrated implants for the attachment of prostheses are known in various applications, including the fixation of dental prostheses and orbital prostheses. Typically, these osseointegrated implants include certain common elements. Usually, a screw shaped fixture, typically of titanium, is surgically implanted and allowed to osseointegrate into the bone. A skin penetrating element, an abutment, also typically of titanium, is attached to the screw shaped fixture. A well known osseointegrated implant of this type (known as the Branemark system) developed by Per-Ingvar Branemark is available through Nobelpharma AB, P0 Box 5190 S-402, Goteborg, Sweden.
U.S. Design Pat. No. Des.294,295 issued to Branemark illustrates a typical implant of the type employed in the Branemark system. In the Branemark system a gold bar is fastened laterally between two osseointegrated implants and externally to the patient's skin. Metallic clips embedded in the prosthesis are employed to removable attach the prosthesis by clipping onto the gold bar.
Another type of implant as used in conjunction with a spacing member for attaching a cranial facial prosthesis is disclosed in U.S. Pat. No. 5,593,444 issued to Svensson et al. Svensson et al. discloses a spacing member arranged between a securing element implanted in the facial bone and an extraoral prosthesis.
U.S. Pat. No. 5,064,374 issued to Lundgren discloses an implant structure comprising a central portion which can be attached to an implant fixed anchorage element and two projecting wing like structures to form a unitary bridge body.
In another type of fixation method, a pair of strong magnets may be employed, one affixed to the prosthesis and the other affixed to the osseointegrated implant. U.S. Pat. No. 5,425,763 discloses such a magnet arrangement for attaching prostheses to an osseointegrated implant.
There are a number of limitations to the prior art techniques for attaching a prosthesis to an osseointegrated implant. One is that the repeated attachment and removal of the prostheses can weaken the osseointegrated fixture. Another problem is that in some applications, such as orbital prostheses, limited space is available for fitting the prosthesis and fit is critical both for aesthetics and comfort. The prior art fixation techniques reduce the space available for the prosthesis.
These and other limitations of the prior art are overcome by the present invention.